Guest
Burning questions about the universe: 1. What was there before the beginning of the universe? everyone asks this question. what’s the simple answer? Oh. I I’m delighted I can respond to you - we don’t know. But we got top people working on it. you know what? there may have been a Multiverse. there might have been a Multiverse, that’s birthing universes and we’re one of them, but that just pushes the question one step further before that - “what was around before the Multiverse?“ - so, we just don’t know. it’s a frontier question right now. 2. How will the universe end and what will there be afterwards? We have several ideas for how it will end. It’ll just continue to expand forever as the temperature descends asymptotically towards absolute zero and all phenomenon and all processes will cease. All Stars will burn out. they will shut off in the night sky one by one and the universe will be cold and dark. But if the expansion of the universe which is rapid and accelerating is real and continues, that’ll take us to the Big Rip, that terrifies me, because if the fabric of the universe stretches faster, than the con, than the material substance can’t sustain it. then it rips... but that’s in 22 billion years. that is the only comforting part. 3. Is the universe infinite and if not what’s on the other side of it? So, the observable universe has a boundary. it’s not a physical boundary. it’s a consequence of how fast the light travels and how old the universe is, so that sets a horizon. a ship at Sea, there’s a horizon. Is the ship captain saying - is this all there is or does the ocean go on? and they know from their experience, the ocean continues. we’re pretty sure the Universe goes well beyond our Horizon. we don’t know how far and it’s possibly infinite and if it is infinite, then it wouldn’t make sense to talk about an edge. then the above question becomes Superfluous. 4. Is time travel possible? We can definitely travel into the future by moving faster relative to everybody else and then you’ll come back less aged than those you left here on Earth. The tricky part comes if you want to go into the past and that’s really dangerous. it is so dangerous, that Hawking was thinking to himself, that there must be some law of physics we have yet to discover, that prevents it. physically it’s called a time travel protection conjecture. Because if you go back and prevent your parents from meeting each other, then you will never be born to go back in time to prevent your parents from meeting each other and this whole thing with the Terminator movie where he’s killing everybody, who might give birth to the person, who’s going to overthrow the regime, all you have to do is prevent people from meeting each other or have them have sex 10 minutes later or earlier, than they might have otherwise and a different sperm would have fertilized the egg and you got a different person. all shoot, it was so needlessly violent. so yeah, it might not be likely that we can do this, but there are equations in the general relativity that allow it. Hawking just wondered whether we’ll come up to a bound a rule, that says “nope, nope“. The equation tells us, that it is possible to travel in the past, but a higher understanding of the universe might actually prevent it. 5. Parallel universes... do they exist? All our current understanding of how this universe got here, tells us, there are plenty of other universes and that’s the Multiverse idea and parallel universe sounds a little more cool, than just other universes in a Multiverse, but sure, there’s likely an infinite number of them. all combinations of all atoms and molecules and thoughts and neurosynaptic firings would exist in the infinite universes. there could be a parallel universe where dreams are reality and realities are dreams, or where stars are gazing down at you, rather than you gazing up at the stars. There’s a lot of variations and some of these universes would have it slightly different laws of physics, so you don’t want to visit them without full understanding of the consequences of that. Uou don’t want to collapse into a pile of goo, because the molecular forces that previously held your body together in this universe don’t work in the other universe. That would be a dangerous, dangerous freeways to take.
